Motor-compressor unit



Sept 5., 1933. R. w. DAVENPORT 1,925,556

MOTOR COMPRESSOR UNIT Filed Feb. 27, 1929 lHlll IN1/EN TOR. Pansa/77 h(m/@npar BY l A TTORNE Y.

Patented Sept.l 5, 1933 UNITED STATES PATENT ori-Fics Moron-COMPRESSORUmm;

Application February 27, 1929. Serial No. 343,177

Claims.

This invention relates to apparatus used in the transforming of heat andparticularly concerns means for freeing vaporized refrigerant fromentrained lubricant. While of general util- 5 ity it has directapplication to refrigerating systems of the closed cycle type in whichthe lubricant used is partially or fully soluble in the refrigerant. Ithas been developed and is specially ,intended for use in systemsoperating in accordancewith the process disclosed in my Patent No.

1,698,938, issued January 15, 1929. More specifically it concerns thedynamic means for circulating the refrigerant solution.

One object of the invention is to provide an l5 improved pump orcompressor unit which is particularly adapted for a lubricant which issoluble in the working medium or refrigerant. Another object is tosecure adequate lubrication of the moving parts of the apparatus withoutimpairing the heat transforming effects of the system, and vice versa.-Other important objects will be apparent from the detailed descriptionwhich follows.

In a refrigerating system operating in accordance with the process setforth in my patent above identified, a solution of lubricating oil inrefrigerant liquid is alternately concentrated and diluted whileevaporating vto absorb heat and condensing to eject heat, respectively.The lubricant 0 and the volatile refrigerant are caused to vary in theirrespective proportions. In the pump the solution should be practicallyall lubricant While in the refrigerating evaporator the solution shouldbe practically all volatile liquid. As volatile liquids are thin and oflow viscosity and film strength, they are not suitable as lubricants forthe purpose of floating bearings orfor sealing clearance spaces.Furthermore, as the vapor tension o f liquids suitable for refrigerationis rather high, any considerable proportion of refrigerant in thelubricant in the compressor would result in transferring therefrigerating eiect from the evaporator to the compressor itself. Anysuitable methods and apparatus may be used for concentrating thesolution suflicientlyV to use the same for lubricating purposes beforethe solution reaches the pump. But to maintain the lubricant at properviscosity in the pump,

y the lubricant must be kept away from contact vinvention since areciprocating piston pump could and at .the same time maintaining theviscosity of the lubricant at a satisfactory high point.

According to the present invention, the pump is provided with means forkeeping the lubricant and the refrigerant vapor, discharged together bythe pump, so far as possible out of heat exchanging relationship Withthe pump and with other apparatus while the suspended oil is beingseparated. The invention also provides for collecting and distributingthe separated lubricant 6 to the parts requiring lubrication whilemoving the hot vapor directly to the condenser and away from thelubricant. By preference the motive agent for the pump, such as anelectric motor, is mechanically connected with the pump by way of asingle common shaft and is also pneumatically and hydrostaticallycombined with the separating means and with the pump, the entirevcombination being sealed so as to afford a wholly self-contained machineor unit suitable for use in mechanical refrigerating systems of theclosed cycle compression type. A

In order to illustrate the invention one concrete embodiment thereof isshown in the accompanying drawing, in which:

Fig. 1 is a longitudinal sectional view through a totally enclosed andsealed motor pump unit; Fig. 2 isa transverse sectional view through thepump portion of the unit substantially on the line '2-2 of Fig. 1;

Fig. 3 is a right end elevational view of the pump alone and indicatesdiagrammatically the manner of connecting the same into a compressionrefrigerating system; and

Fig. 4 is a fragmentary sectional view of the motor pump unit shown inFigs. 1 and 2, the sectioned portion of the pump being indicated by thebroken line 4--4 of Fig. 3.

In the embodiment of the invention chosen for the purpose ofillustration, a rotary pump of the stationary abutment or blade type isshown, but itis to be understood that the particular type of pump has norelation` to the spirit of the the motor. The lower portions of bothpump casing 5 and motor casing 7 provide a reservoir for lubricant whichis maintained at a sucient level to cover at least the lower portion ofthe abutment plate 9 which is maintained in contact with piston 10 ofthe pump by springs 11. The pump has a single uid inlet connection 12(Figs. 2 and 3) and a single outlet connection 13 (Figs. 3 and ll).Since specific forms of pump and motor are not essential to the presentinvention, further description of pump A and motor B is omitted. A

Fig. 3 illustrates diagrammatically one method of connecting a pump, orthe pump unit illustrated in Fig. 1, into a closed cycle refrigeratingsystem utilizing as a working substance a lubricant in solution with avolatile liquid. The outlet 13 of the pump is connected to a condenser:r where heat is extracted from the hot vapors issuing from the pump andwhence condensate is fed through an expansion devicey into an evaporator.e connected to inlet 12 of the pump. Evaporator z is arranged to effectconcentration of the lubricant solution in accordance with the processdescribed in my aforementioned patent and may be of the form disclosedin my copending application Serial No. 151,671, led November 30, 1926,now Patent No. 1,769,017 issued July 1, 1930.

Since the temperature of the pumpwill vary with changes in environingtemperature, and especially when it is arranged for intermittentoperation as in automatically controlled refrigerating systems, it ishighly important that lubricant within the pump be maintained at itsproper viscosity so that there will not be undue wear of working partsand so that the pump will operate with proper eiiiciency. To this end itis essential that the hot refrigerant vapor pass as quickly as possibleto condenser a: and be kept out of contact with the reservoir oflubricant in the motor pump unit. Moreover, the level of lubricant invthe reservoir must be maintained by separating the consists of amixture of refrigerant and oil vapors with the oil vapor constitutingonly a small percentage of the total because the oil vapors tension ismuch lower than that of the refrigerant. The hot liquid consists of asolution of refrigerant in oil wherein for the same reason theproportion of oil is greatly in excess of the refrigerant. Theproportions of oil and refrigerant in both the vapor and liquid dependwholly upon the temperature and pressure if constant, or upon the rateof change if the temperature and pressure vary. The separating meansabout to be described are arranged to function so that the drops ofliquid may be caused to separate from the vapor without substantialchange in the relative proportions of oil and `refrigerant with theresult that the liquid will remain nearlyall lubricant.

Upon issuing from passage 14, the stream of vapor and suspendedlubricant passes a check or discharge valve 15 supported in a Valveblock 15a into a discharge chamber 16 which may be partly full oflubricant solution to mufle the sound of discharge. The vapor andsuspended oil pass through chamber 16 upwardlythrough a conduit From thepump, whateverI 17 provided with a ilaring mouth 17a which directs thesame against one or more baffles 18 and separators 19 in a separatingchamber 20. The separating means may be of any well known type but areindicated as in the form of baffle plates and screens respectively. Theseparated lubricant falls down around conduit 17 and i'llls a trap 21whence it overows into a chamber 22 into which the bored end of shaft 8extends so that the separated lubricant fills bore 8a and the lubricantis distributed to the bearings and working parts of the motor and pump.Any excess of of lubricant in chamber 22 is conducted by a passage 23(Figs. 2, 3, and ll) into the motor chamber of the motor pump unit,where it drops into the reservoir of lubricant in the base of the unitwhence it leaks back into the compression space around the slidingmember 9.

For convenience of manufacture and assembly, the conduit 17 betweendischarge chamber 16 and separating chamber`20, and the trap 21 whichseals the separating chamber from the passage for separated lubricant,may be combined in a single insert unit formed of sheet material asshown in Fig. 4. The lower part of this insert has double walls in tightengagement which serve to seal the opening between chamber 22 of thelubricant passage and discharge chamber 16; thereabove these wallsdiverge, the inner wall forming the conduit 17 for the discharge and theouter arranged in spaced relation with the inner wall to form theannular chamber of the liquid seal or trap 21. Still another wall member24 serves as a bushing and seal for the opening between separatingchamber 20 and lubricant chamber 22 and extends between the spaced wallsof the trap chamber 21 and well down toward the bottom of the same sothat the separated lubricant from chamber 20 must take a tortuous paththrough trap 21 to reach chamber 22, the lubricant retained in the trapchamber forming a liquid seal. 1t is thus apparent that while chambers16, 22, and 20 provide an ascending series as indicated at Fig. 3, theinsert member just described serves directly to connect chambers 16 and20 and then to provide a connection for liquid only between chambers 29and'22 and a barrier against the passage of the gasses and vapors inchamber 20.'y

It is to be particularly noted that the body of lubricant in the mainreservoir in the base of the motor pump unit is sealed oi from Yanybodies of lubricant in discharge chambers 16 and 20 by the trap 21 sothat hot vapor from the rst named chambers cannot enter the main casingof the unit but can only go on through the separating chamber 20 andoutlet connection 13 to the condenser. This is an essential part of theinvention. If the hot vapor were to be brought back into contact withother parts of the housing, condensation would result not only inthinning out the lubricant but in robbing the refrigerating evaporator zof its refrigerant, especially when the motor pump is cool. In carryingout the invention it is further advisable that the mass and the capacityof separating chamber 20 and the connection thereto, including chamber16 and conduit 17, be kept low and out of heat exchanging relation withthe pump so far as possible. For this purpose these chambers areprovided in the small closure member 6 at one end of the motor pumpunit.

While the invention is herein described in what is now considered to bea preferred form, it is to be understood that the invention is notrestricted 'of lubricant retained in said separating chamber,

and means in said passage continuously providing a liquid seal toprevent vapor from passing therethrough.

2. A pump for use in heat transforming systems comprising a casingproviding a lubricant reservoir, a discharge chamber and a separatingchamber in superposition, baille means in said last named chamber forfacilitating the separation of vapor from lubricant entrained therewith,a passage leading from said separating chamber to the working parts ofsaid pump and to saidv reservoir, and means disposed between saidchambers for interconnecting the same and for continuously providing aliquid seal between said discharge chamber and said passage.

3. A pump for use in heat transforming systems comprising a casingproviding a lubricant reservoir, a discharge chamber and a separatingchamber, a passage leading from said separating chamber to the workingparts of said pump and to said reservoir, and an insert between said-chambers providing a direct connection therebetween but a tortuousconnection from said separating chamber to said passage arranged toprevent the passing of vapor to the latter.

4. A pump for use in heat transforming systems comprising a casingproviding a lubricant reservoir, a discharge chamber and a separatingchamber, baiiie means in said last named chamber for facilitating theseparation of vapor from lubricant entrained therewith, a passageleading from said separating chamber to the working parts of said pumpand to said reservoir, and a combined conduit and trap member interposedbetweensaid chambers to interconnect the same and to provide a liquidseal in the connection between said separating chamber and said passage,said member being formed centrally and axially as a conduit between saidchambers and having an outwardly flared end directly beneath said baillemeans.

5. In a heat transforming apparatus, a pump. an electric motor foroperating said pump, said pump and motor having a common shaft and beingtotally enclosed to form a sealed motor pump unit, the lower part of theinclosure of both said motor and pump forming a reservoir for lubricant,passages for conducting lubricant to the bearings and moving parts ofboth said motor and pump including a bore in said shaft, and meanswholly within said unit including superposed discharge and separatingchambers for separating and trapping out of the discharge stream of thepump the entrained lubricant, for feeding the same to said passages, andfor conducting the excess to said reservoir.

RANSOM W. DAVENPORT.

